A next-generation communication system of the W-CDMA (Wideband Code Division Multiple Access) system, HSDPA (High Speed Downlink Packet Access) system, HSUPA (High Speed Uplink Packet Access) system and the like, namely an LTE (Long Term Evolution) system has been studied by 3GPP (3rd Generation Partnership Project) which is a standards body of the W-CDMA. In the LTE system as a radio access system, an OFDM (Orthogonal Frequency Division Multiplexing) scheme and an SC-FDMA (Single-Carrier Frequency Division Multiple Access) scheme have been studied as prospective candidate schemes to be applied to the downlink communications system and the uplink communications system, respectively (see, for example, Non Patent Document 1).
The OFDM scheme is a multi-carrier transmission scheme in which a frequency band is divided into plural sub-carriers having narrower frequency bands, and data are mapped onto the sub-carriers. By closely and orthogonally arranging the sub-carriers along the frequency axis, faster transmission is expected to be achieved and the efficiency of using the frequency band is also expected to be improved.
The SC-FDMA scheme is a single carrier transmission scheme in which a frequency band is divided with respect to user equipment (hereinafter may be referred to as a user equipment (UE) terminal or a mobile station) in a manner so that different frequencies can be separately used among plural terminals (user equipment (UE) terminals); and as a result, interference between terminals may be easily and effectively reduced. Further, preferably, in the SC-FDMA scheme, a range of transmission power fluctuation may be made smaller; therefore, lower energy consumption of terminals may be achieved and a wider coverage area may also be obtained.
In both uplink and downlink of the LTE system, communications can be performed by allocating one or more resource blocks to the mobile station. More specifically, the resource blocks may be shared among plural mobile stations in the system. In the LTE system, the base station (hereinafter may be referred to as a base station apparatus) determines which resource blocks are to be allocated to which mobile station from among plural mobile stations with respect to each sub-frame having 1 ms period (this allocation process may be called Scheduling). The sub-frame may also be called a TTI (Transmission Timer Interval). In downlink, the base station apparatus transmits a shared channel using one or more resource blocks to the mobile station selected by the Scheduling. The shared channel is called a Physical Downlink Shared Channel (PDSCH). In uplink, the mobile station selected by the Scheduling transmits the shared channel using one or more resource blocks. This shared channel is called a Physical Uplink Shared Channel (PUSCH).
In a communication system using the shared channels, it is required to perform (report) Signaling designating which shared channel is allocated to which user equipment terminal. In the LTE system, a control channel used for the Signaling is called a Physical Downlink Control Channel (PDCCH) or a Downlink L1/L2 Control Channel (DL-L1/L2 Control Channel). The Physical Downlink Control Channel (PDCCH) may include information items such as Downlink Scheduling Information, Acknowledgement information (ACK/NACK), Uplink Scheduling Grant, an Overload Indicator, Transmission Power Control Command Bit and the like (see, for example, Non Patent Document 2).
The Downlink Scheduling Information and the Uplink Scheduling Grant correspond to the information on which the Signaling is to be performed (i.e., to be reported as Signaling (information)). The Downlink Scheduling Information includes the information of the shared channel in downlink. More specifically, the Downlink Scheduling Information includes allocation information of the Resource Blocks in downlink, identification information of the user equipment (UE) terminal (UE-ID), data size, a modulation scheme, information items indicating an HARQ (Hybrid Automatic Repeat reQuest) and the like. When a MIMO (Multi-Input Multi-Output) system or a multi-antenna system is applied, the Downlink Scheduling Information further includes the number of streams and the information of Precoding Vectors.
The Uplink Scheduling Grant includes information of the shared channel in uplink. More specifically, the Uplink Scheduling Grant includes allocation information of the Resources in uplink, the UE-ID, data size, modulation scheme, information of transmission power in uplink, information of a Demodulation Reference Signal in Uplink MIMO and the like.
In downlink, a Common Control Physical Channel (CCPCH) is also transmitted. The Common Control Physical Channel (CCPCH) typically includes a Broadcast Channel (BCH). The Broadcast Channel (BCH) transmitted via the Common Control Physical Channel (CCPCH) may be especially called a static Broadcast Channel or a Primary Broadcast Channel (P-BCH). This is because there are some other broadcast channels called a Dynamic Broadcast Channel (Dynamic part) and a Secondary Broadcast Channel (S-BCH). The Dynamic Broadcast Channel is mapped onto the Physical Downlink Shared Channel (PDSCH). In this case, the Downlink Scheduling Information for the Dynamic Broadcast Channel is transmitted via the Downlink L1/L2 control channel (DL-L1/L2 Control Channel).
An uplink control channel transmits a downlink Channel Quality Indicator (CQI), the Acknowledgement information with respect to the Physical Downlink Shared Channel (PDSCH) and the like. The Channel Quality Indicator (CQI) is used in, for example, the Scheduling process and an Adaptive Modulation and Coding Scheme (AMCS) with respect to the Physical Downlink Shared Channel (PDSCH).
Non Patent Document 1: 3GPP TR 25.814 (V7.0.0), “Physical layer Aspects for Evolved UTRA,” June 2006
Non Patent Document 2: 3GPP R1-070103, Downlink L1/L2 Control Signaling Channel Structure: Coding